Method of manufacturing lock nuts



April :20, 1943. R. o. cHAFFEE v2.31109 v LETHODf0F MANUFACTURING LOCK NUTS Filed oct. 17, 1941' 24 sheetss1ieef,2

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Patented Apr. 20, 1943 METHOD F MANUFACTURING LOCK NUTS Raymond 0. Chaffee, Belmont, Mass., assigner to United-Carr Fastener Corporation, Cambridge, Mass., a corporation of Massachusetts Application October 17, 1941, Serial No. 415,392

(Cl. l086) 4 Claims.

This invention relates to a method of making a lock nut.

The lock nut disclosed is of a type now in commei-cial use, providing spaced tapped portions and resilient folding wing-like portions, connecting the tapped portions. The wing portions are moved from substantially straight form to folded forni by collapsing the nut axially at one stage in the process of manufacture of the same, and the object of my present invention relates chiey to a method of stiiiening the wings at predetermined points on their lengths insuring that the wings ilex at proper points during the operation by which they are set into folded form.

Other objects and uses of my invention will be apparent from inspection of the drawings and specification hereinbelow set forth.

Referring to the drawings in which I have illustrated a preferred embodiment of my inventieni Fig. l is a top plan view of a completed nut formed by the improved method hereinbelow set forth;

Fig. 2 is a side elevation of the nut shown in Fig. 1;

Fig. 3 is a side elevation with the nut turned 90 from its position of Fig. 2;

Fig. 4 is a view similar to Fig. 3 and showing the nut blank prior to the embossing operation;

Fig. 5 is a sectional View showing a die block carrying a nut blank and a punch block in operating position;

Fig. 6 is a view of the nut blank shown in Fig. 4 with the nut blank turned 909;

Fig. 7 is a sectional view similar to Fig. 5, showing the tools in closed die position;

Fig. 8 is a side elevation of the nut blank after the embossing operation;

Fig. 9 isa view showing the embossed nut blank inserted in a die and in position immediately prior to the operation by which it is collapsed;

Fig. 10 is a view similar to Fig. 9 showing the nut blank in one step of the collapsing operation; and

Fig. 11 is a view showing the nut blank after completion oi' the collapsing operation.

Referring to the drawings I have shown in Figs. 1-3 a nut member I in finished form and constructed by my improved method. The nut member I is a. type of lock nut now being manu- Iact'ured in large quantities for commercial use and the form of the finished article comprises no part of my present invention, except as related to the improved method which I have derived for manufacturing the same.

The completed nut I has a base 2, a tapped body i portion 3 projecting from the base 2, a tapped end portion d and a pair of opposed folded resilient wings 5 connecting the tapped portions 3 and 4. The body portion 3 and end portion 4 provide threads of the same pitch, but the thread lead of one portion is thrown out of phase with the lead of another. pands as the nut is screwed on the bolt and thereafter tends to contract under the tension set up in the Wings 5 during the threading operation so as to exert axial tension upon the bolt preventing the nut from moving on the bolt.

Setting. out briefiy the steps in the manufacture of the nut prior to that step of the process to which my present invention is particularly directed, a barrel is first pressed from a strip of sheet metal by a series of drawing operations. The barrel has a constant inner and outer diameter throughout its length and is open at both ends. The blank thus formed is then subjected to a stabbing operation forming opposite openings in diametrically opposed sides of the barrel at predetermined points along the length of the barrel. The blank is now of the form shown in Figs. 4 and 6 of the drawings and provides a base 6, lower ring-like portion 'l and an upper ring-like portion 8 joined by straight connecting portions 9. The connecting portions il are in diametrically opposed relation and spaced from each other circumferentially of the barrel by the stabbed openings I0. The blank is now ready for the embossing operation which is the step in the process to which my invention is particularly directed and in Fig. 5 I have illustrated `the tools by which the embossing is preferably accomplished.

Referring to Fig. `5 I have shown a die block I l having a central die insert I 2.- The die block has horizontal slots I3 which intersect the die insert I2 and carry reciprocable punches I4. A cover plate I5 maintains the punches I4 in assembly with the die block and providesa central opening I6 through which the die insert extends. The cover plate also has a pair of openings II of predetermined size overlying the slots I3. Each of the punches I4 carries a projecting pin I8 permanently afllxed to the punch as by a drive nt. The pins I8 extend from the punches into the openings I'I and are of smaller diameter than the openings l1 with the resun that the wens of the openings cooperate with the pins I8 to limit inward movement of the punches. Each of the punches I4 carries a cam roller III at its outer As a result, the end portion d ex- 1 end in alignment with the bore of the cam bushing 2|.

In Fig. 5 I also have illustrated a punch block 22, carrying a pilot 23 received within a. bushing 24. The block 22 also carries a pair of cams 25 adapted to actuate the punches I4 when, the die is closed. In operation of the tools the nut blank is positioned in the die insert of the die block with the connecting portions 9 in alignment with the slots I3 as shown in Fig; 5. When the die is clsed the pilot pin 26 enters the vbore of the nut barrel to support the same, `after which the cams engage the rollers I9 driving the punches I 4 inwardly. Each of the punches I4 has a pair of projections 21 at its inner end which, under the force applied to the punches by the cams 25, strikes the connecting portions 8 of the nut blank causing opposite pairs of dimples or embossments 28 preferably of the shape shown in Fig.v8 to be formed in the connecting portions. The projections 21 of each punch. are spaced a predetermined distance effecting a corresponding spacing of the embossments 28 for a purpose to be described. After the embossments have been formed the barrel is ready to be col lapsed axially.

In my preferred method of collapsing the barrel, the barrel'is moved onto a mandrel 29 projecting from the outer face of a die 30 so that when the parts are in position to receive the punch the base 6 of the nut blank is supported by the face of the die and the inne'r Wall of the nut barrel is supported by the mandrel as shown Y in Fig. 9. A punch 3| provides a face 32 having a recess 33 and a projecting lip 34 surrounding and adjacent the recess. The .recess 33 is of a predetermined depth to control the pivot points of the connecting portions 9 adjacent the upper ring 8 in the first stages of compression and the lip radius thereafter operates to eiect proper bending of the portions.9. Prior to my present invention it was found that the points at which the connecting portions 9 started to flex or bend to form the loops were variable, resulting, in many cases, in overfatigue of the metal and consequent cracking of the loops. Also, it was -found that if the connecting portions did not crack during the setting operation the resulting loops were often uneven and consequently unsatisfactory. The purpose of forming the dimples in the connecting portions 8 by the method hereinabove described is to stiffen the metal at pre- 'determined points along the lengths. Thus, the pressure upon the metal of the connecting portions 9 in forming the dimples 28 works vthe metal so as to make points of the connecting portions at the dimples more resistant to bending than points of the non-worked portions. The dimples are formed at predetermined points along the lengths of the connecting portions so that, as most clearly shown in Fig. 10, three bending points are provided for each connecting portion, namely, between the ring 'I and the dimple in closest proximity, between the`pair of dimples and between the ring 8 and the dimple nearest to thesame. The three bending points are shown by the dotted lines of Fig. 9, marked A-A, B-B, and C-C. The dimples serve to control the bending points throughout the setting operation and as a, result the connecting portions fold evenly into proper shape when the barrel is collapsed.

After initial collapse of the barrel has been completed so that the barrel is substantially of the form shown in Fig. 11, a tap is run through the ring portions l and 8. Thereafter, the ring portions are moved toward each other causing the threads to take the out of phase relation which effects the desired locking action.

Although I have illustrated and described a. preferred embodiment of my invention, I do not wish to be limited thereby as the scope of my invention is" best defined by the following claims.

I claim:

` 1. The method of manufacturing a lock nut having a threaded body portion, a threaded end portion and resilient folded portions therebetween which comprises taking a blank having a body portion, an end portion and a pair of opposed connecting elements Joining said portions, forming a pair of spaced indentations in the metal of each of said connecting elements so as to stiffen said respective elements at said indentations, and compressing the blank axially causing each of said connecting elements to bow outwardly at a point intermediate said indentations.

2. The method of manufacturing a lock nut having a threaded body portion, a threaded end portion and resilient folded portions therebetween whichl comprises taking a. blank having a base and a hollow barrel, forming opposed openings in said barrel intermediate the ends thereof defining spaced connecting portionsjoining a pair of ring-like portions, forming a pair of spaced indentations in the metal of each of said connecting elements so as to stiifen said respective elements at said indentations. and compressing said barrel axially causing each of said con necting elements to bow outwardly at a point intermediate said indentations.

3. The method of manufacturing a lock nut having a threaded body portion, a threaded end portion and resilient folded portions therebetween which comprises taking a blank having a base and a hollow barrel, forming opposed openings in said barrel intermediate the ends thereof defining spaced connecting portions joining a pair of ring-like portions, forming a pair of indentations in the metal of each of said connecting elements so as to stiffen said respectivel ele` ments at said indentations. said indentations of each of said ,iairs being spaced one from another and each of said indentations being spaced from salad respective ring portions adjacent thereto, and compressing said barrel axially causing said elements to flex at points intermediate said indentations and said adjacent ring portions and intermediate said pairs of indentations.

4. The method of manufacturing a. lock nut having a threaded body portion, a threaded end portion and resilient folded portions therebetween which comprises taking a blank having a body portion, an end portion and a pair of opposed connecting elements joining said body portion and end portion, forming a pair of spaced indentations in said connecting elements so as to stillen said respective elements atvsaid indentations, compressing the4v blank axially causing each of said connecting elements to bend between the non-indented portions thereof, tapping said blank to thread the body and end portions and finally moving the threaded portions axially put of phase with relation to each other.

RAYMOND O. CHAFFEE. 

